A Sinn Fein senator suspended after retweeting an offensive message about the IRA killing of prison officer Brian Stack has formally apologised to his family.
Maire Devine told the Seanad she wanted to say sorry for the "offence and hurt" caused.
Mr Stack, a chief prison officer in Portlaoise, was shot in the neck by the IRA in March 1983 and died 18 months later.
Ms Devine was suspended by her party for three months after she retweeted a message that used an offensive phrase to describe Mr Stack on March 18.
She told fellow senators on Tuesday that she thought the tweet she retweeted was genuine and had not read its full content.
She added: "A number of follow-up tweets from me were wholly inappropriate and I deeply regret that.
"I want to again apologise for any and all offence and hurt that was caused by my Twitter activity. It was never my intention to cause any more hurt to those already in deep distress.
"I want to put on the record my most sincere apologies to the family of the late Brian Stack."
It was not until 2013 that the IRA admitted responsibility for Mr Stack's death, the only prison officer murdered in the Republic during the Troubles.
He was left paralysed and brain-damaged by the shooting as he crossed a road outside the National Stadium in Dublin in late March 1983.
He suffered for 18 months before dying from his injuries at the age of 47.
The incident was the latest social media furore to hit Sinn Fein. In January West Tyrone MP Barry McElduff resigned over a Twitter posting about the 1976 Kingsmill shootings.